This invention relates to a brightness equalizing light filter system used in conjunction with an indirect fluorescent light fixture.
A current problem with existing indirect, fluorescent light fixtures is that they appear dark as viewed against the relatively evenly illuminated ceiling which they light. This is a particular problem in an environment where people work at video display terminals, where the dark underbodies of such fixtures provide a distracting reflection on the CRT screen.
It would be desirable if the fixture itself could be illuminated to a brightness approximately that of the ceiling. One method to accomplish this would be to make the bottom surface of the fixture translucent, allowing some light to "leak" from the fluorescent source through the bottom of the fixture. However, due to the proximity of the light source to the translucent panel, a bright spot, or line, will appear near the center line of the panel with an apparent brightness much greater than that of the ceiling or the rest of the panel. This bright spot may be reduced by employing a second translucent panel and/or by integrating a pattern into the panel so as to block some of the light passing through.
One difficulty encountered in trying to design a light diffusing translucent bottom for the fixture is that the conventional types of fluorescent lamps, that is the rapid-start lamps, will not operate correctly unless a grounded metal plate or reflector is in close proximity to the lamps. This grounded metal plate serves as a "starting aid" and is necessary to quickly establish the required arc without undue flickering when the lamps are turned on.